How the theory of self-organized criticality explains punctuated equilibrium in social systems

Punctuated equilibrium is a characteristic of some natural and social systems that occasionally generate bursts of activity at different scales following periods of stagnation of different durations. This phenomenon can be formalized as pink noise, which is an attribute of self-organized criticality (SOC). This paper outlines the main ideas of the SOC theory and the tools for identifying pink noise. It presents examples of punctuated equilibrium found in computer experiments with artificial societies, as well as in historical and political studies. Such examples are found, in particular, in demographic processes, in the development of markets, in the dynamics of electoral choice, in the Internet activity of network communities, in terrorist and criminal activity, and in protest movements in the past and present. The SOC theory explains why avalanche-like social transformations do not always occur under the influence of some major extraordinary factor. Social cataclysms can be caused by the intrinsic properties of systems as well as by micro-level processes and local impulses. Internal transformational potential can be high enough and, at the same time, subtle. The SOC theory describes the ways in which such avalanche conditions can be identified with mathematic rigor and, at the same time, relatively easily.

Investigation of Multilayer Nanostructures of Magnetic Straintronics Based on the Anisotropic Magnetoresistive Effect

The article presents the results of experimental studies of multilayer nanostructures of magnetic straintronics formed by magnetron sputtering on a 100 mm silicon wafer. The object of the study is two types of nanostructures: Ta/FeNiCo/CoFe/Ta and Ta/FeNi/CoFe/Ta, differing in the ratio of magnetic layers. The magnetic and magnetoresistive characteristics of multilayer nanostructures under varying mechanical loads are studied both on a 100 mm wafer and in the form of 4 × 20 mm² samples of two types. The first, where the axis of easy magnetization is directed along the long side of the sample, and the second, where the axis of easy magnetization is a tilt at 45°. Based on the obtained data, the conclusions about the practical application of these nanostructures in magnetic straintronics elements are drawn.

Progressive lysosomal membrane permeabilization induced by iron oxide nanoparticles drives hepatic cell autophagy and apoptosis

Iron oxide nanoparticles (IONs) are frequently used in various biomedical applications, in particular as magnetic resonance imaging contrast agents in liver imaging. Indeed, number of IONs have been withdrawn due to their poor clinical performance. Yet comprehensive understanding of their interactions with hepatocytes remains relatively limited. Here we investigated how iron oxide nanocubes (IO-cubes) and clusters of nanocubes (IO-clusters) affect distinct human hepatic cell lines. The viability of HepG2, Huh7 and Alexander cells was concentration-dependently decreased after exposure to either IO-cubes or IO-clusters. We found similar cytotoxicity levels in three cell lines triggered by both nanoparticle formulations. Our data indicate that different expression levels of Bcl-2 predispose cell death signaling mediated by nanoparticles. Both nanoparticles induced rather apoptosis than autophagy in HepG2. Contrary, IO-cubes and IO-clusters trigger distinct cell death signaling events in Alexander and Huh7 cells. Our data clarifies the mechanism by which cubic nanoparticles induce autophagic flux and the mechanism of subsequent toxicity. These findings imply that the cytotoxicity of ION-based contrast agents should be carefully considered, particularly in patients with liver diseases.

Intravital microscopy reveals a novel mechanism of nanoparticles excretion in kidney

Developing nanocarriers that accumulate in targeted organs and are harmlessly eliminated still remains a big challenge. Nanoparticles (NP) biodistribution is governed by their size, composition, surface charge and coverage. The current thinking in bionanotechnology is that renal clearance is limited by glomerular basement membrane pore size (≈6 nm), although there is a growing evidence that NP exceeding the threshold can also be excreted with urine. Here we compare biodistribution of PEGylated 140 nm iron oxide cubes and clusters with a special focus on renal accumulation and excretion. Atomic emission spectroscopy, fluorescent microscopy and magnetic resonance imaging revealed rapid and transient accumulation of magnetic NP in kidney. Using intravital microscopy we tracked in real time NP translocation from peritubular capillaries to basal compartment of tubular cells and subsequent excretion to the lumen within 60 min after systemic administration. Transmission electron microscopy revealed persistence of intact full-sized NP in urine 2 h post injection. The results suggest that translocation through peritubular endothelium to tubular epithelial cells is an alternative mechanism of renal clearance enabling excretion of NP above glomerular cut-off size.

How to measure trust: the percolation model applied to intra-organisational knowledge sharing networks

Purpose

The present paper aims to explore how to measure trust as a receptivity force in an intra-organisational knowledge-sharing network with the help of self-developed algorithms of modelling percolations.

Design/methodology/approach

In this paper, a completely new methodology is applied by using a sample study of an international company’s financial centre as an example. Computer software has been developed to simulate the network and calculate the percolation thresholds by combining its characteristics, thereby revealing what and to what extent connectivity and trust, respectively, influence knowledge sharing.

Findings

The application of computer modelling to build up a percolation network is useful for answering questions about the determinants of knowledge sharing. Arguably, the authors demonstrate how the applied new methodology is superior in addressing how to measure the critical values of trust, connectivity and interaction issues, as well as leading to better insights about how these can be managed. The present paper confirms that trust is an essential factor influencing knowledge sharing and that there is a reciprocal effect between social interaction and trust.

Practical implications

The model provides a useful tool for assessing features of the intra-organisational knowledge-sharing network and thus an important foundation for implementing actions in practice. The findings of this study imply that managers should consider the important role of task-related trust between actors and in general for knowledge sharing. With the help of percolation modelling, the degree of trust in an organisation can be computed, and this provides managers with an approach for managing trust.

Originality/value

The topic of “how can trust be measured” is very important and is becoming even more important now because the financial crisis and other issues are raising questions about trust and moral compass rather than financial data. A percolation-based approach to studying knowledge sharing has not been researched in depth before now, and this study attempts to fill that gap. Fundamentally, this multidisciplinary research adds value to the theoretical foundation of the percolation network and research methodology to be used in social sciences and gives an example of their potential practical implications.